The invention relates to valves useful in harsh environments. In particular the invention relates to hermetically sealed plug valves which are remotely operable.
A major problem with valves that are used in harsh environments in which corrosive or toxic fluids or gas are circulated, is that packed glands or seals for the valve actuator can leak and allow circulated fluid or gas to escape to the environment. A need exists, therefore, for a valve that will preclude the possibility of loss of the circulated fluid. It is also desirable to have the capability to remotely sense the condition of the valve and to remotely operate the valve in harsh environments where access to the valve is restricted.
One technique for insuring that a valve is hermetic or leak-proof is to enclose the actuator and gland within a cover which is welded to the valve body. While this technique is effective, access to the valve actuator is restricted. Other less restrictive techniques may involve a compromise of the integrity of the seal. When remote monitoring and control of the valve is desired, either the seal integrity is compromised or the system is necessarily complex. For example, a remote control technique involving the use of a magnetically driven valve actuator located within the valve body or housing is shown in Goetz et al., U.S. Pat. No. 4,195,666. The arrangement in Goetz et al. is complex and has moving parts susceptible to failure in a corrosive environment. The need therefore exists for a simple, reliable and uncompromised hermetically sealed and remotely controllable valve for use in a toxic or corrosive environment.